The effects of SAC alloy composition on aging resistance and reliability

Zhang, Yifei; Cai, Zijie; Suhling, Jeffrey C.; Lall, Pradeep; Bozack, Michael J.

doi:10.1109/ectc.2009.5074043

Cited by 66 publications

(22 citation statements)

References 45 publications

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“…After this point, the variations are small and can be fit with a linear decay. These observations are in agreement with our aging results for testing of larger solder tensile specimens [4][5][6]. In addition to the nanoindentation results from the current paper, we have added our prior tensile testing results (blue curve) to the effective modulus data in Figure 10.…”

Section: Effect Of Aging On Elastic Modulus and Hardnesssupporting

confidence: 92%

“…The corresponding degradations of the hardness over the same period were 39.80%, 42.06%, 43.12% and 45.92%. These percentage reductions with 180 days of aging at 125 C are on the same order as those observed for the elastic modulus (51.00%) and yield stress (43.32%) of SAC105 measured by tensile testing of larger multi-grain uniaxial samples in our prior aging investigations [4][5][6]. The uniaxial samples from prior investigations have been examined using polarized light microscopy, and are known to contain hundreds of grains with a variety of orientations.…”

Section: Effect Of Aging On Elastic Modulus and Hardnessmentioning

confidence: 55%

“…The joint results from nanoindentation (red curve) and tensile creep data from smallscale (10 mm long) uniaxial specimens (pink curve) are included. In addition, the creep rate increases measured in prior studies [4][5] by tensile testing of longer (80-100 mm) miniature bulk uniaxial samples are also shown (blue curve). The increases in the creep stain rates observed for the four joint samples were very similar to those measured for the small 10 mm tensile specimens.…”

Section: Effect Of Aging On Creep Responsementioning

confidence: 92%

“…Aging effects on the constitutive and failure behaviors of lead free solders have been studied extensively by the authors and their coworkers [2][3][4][5][6][7][8][9][10][11][12][13][14]. In early investigations, the mechanical properties and creep behavior of SAC alloys were shown to be severely degraded by prior exposure to room temperature (25 C) and elevated temperature (50, 75, 100, and 125 C) aging [2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…In early investigations, the mechanical properties and creep behavior of SAC alloys were shown to be severely degraded by prior exposure to room temperature (25 C) and elevated temperature (50, 75, 100, and 125 C) aging [2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

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Nanomechanical characterization of SAC solder joints - reduction of aging effects using microalloy additions

Hasnine

Suhling

Prorok

et al. 2015

2015 IEEE 65th Electronic Components and Technology Conference (ECTC)

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In this work, we have examined the ability of microalloy additions (dopants) to reduce aging effects in solder joints by nanoindentation testing of several sets of doped/non-doped alloys. The investigated solder joint alloys included SAC105, SAC105+Ni, and SAC105+Mn. For the doped alloys, the base SAC105 solder in the PBGA component solder balls was modified by microalloying an additional small amount (< 0.05%) of the dopant material (Ni, Mn, etc.). The tested joints were extracted from 14 x 14 mm PBGA assemblies (0.8 mm ball pitch, 0.46 mm ball diameter) that were part of the iNEMI Characterization of Pb-Free Alloy Alternatives Project. After extraction, the joints were then subjected to various aging conditions at high temperature (0-6 months aging at T = 125 o C). After aging, the joints were loaded in the nanoindentation system, and the load-deformation behavior during indentation was used to characterize the mechanical properties of the solder joints for various aging conditions including modulus, hardness, and yield stress. Using constant force at max indentation, we have also measured the creep response of the aged and non-aged solder joint materials for various stress levels. With this approach, we have been able to quantify aging effects in joints and compare the behavior of the standard and doped alloys.Our results have shown that addition of the microalloy elements significantly reduced the aging degradations of the mechanical properties and creep resistance in the joints. For example, the average reduction of the effective elastic modulus of SAC105 joints was 32.9% with 180 days of aging, while the analogous average reductions were 7.0% and 8.1% for the SAC105+Ni and SAC105+Mn joints. Similarly, the average hardness (yield stress) degradation for the SAC105 joints was 45.9%, while those for the SAC105+Ni and SAC105+Mn were 10.5% and 10.7%, respectively. Finally, the creep rate increased 69.1X for the aged SAC105 joints, while the creep rate degradations for the SAC105+Ni (6.5X) and SAC105+Mn (9.0X) were an order of magnitude smaller. Our findings have also suggested that the addition of Ni was slightly more effective than Mn for the SAC105+X dopants.

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Section: Effect Of Aging On Elastic Modulus and Hardnesssupporting

confidence: 92%

Section: Effect Of Aging On Elastic Modulus and Hardnessmentioning

confidence: 55%

Section: Effect Of Aging On Creep Responsementioning

confidence: 92%